A printing press typically includes a plurality of printing units which have rotatable cylinders. The cylinders print images onto a web moving longitudinally through the printing units. A printing unit in an offset lithographic printing press, for example, includes a plate cylinder which carries a printing plate and a blanket cylinder which carries a printing blanket. The plate cylinder and the blanket cylinder are supported to rotate in bearings. The printing blanket transfers inked images from the printing plate to the web when the cylinders rotate in the bearings during a printing operation.
Printing units in an offset lithographic printing press are known to include lubricating systems for lubricating the bearings. The lubricating system in such a printing unit includes a grease reservoir, a pump for pumping grease, and a plurality of grease conduits for conveying grease from the grease reservoir to the bearings under the influence of the pump. The pump is actuated periodically during a printing operation to supply quantities of grease which lubricate the bearings.